JP7206787B2 - IMAGE FORMING APPARATUS, IMAGE FORMING APPARATUS CONTROL METHOD, AND IMAGE FORMING APPARATUS CONTROL PROGRAM - Google Patents

Description

The present invention relates to an image forming apparatus, an image forming apparatus control method, and an image forming apparatus control program. More specifically, the present invention relates to an image forming apparatus equipped with a removing means for removing residual toner remaining on the surface of a photoreceptor, a control method for the image forming apparatus, and a control program for the image forming apparatus.

Electrophotographic image forming apparatuses include MFPs (Multi Function Peripherals), facsimile machines, copiers, printers, etc., which have scanner functions, facsimile functions, copying functions, functions as printers, data communication functions, and server functions. be.

An image forming apparatus generally forms an electrostatic latent image using an exposure device on the surface of a photosensitive member charged using a charging device, and develops the electrostatic latent image using a developing device to form a toner image. do. The image forming apparatus uses a transfer roller to transfer the toner image on the surface of the photoreceptor to a sheet of paper, and then uses a fixing device to fix the toner image onto the sheet of paper. Thereby, the image forming apparatus forms an image on the paper.

The image forming apparatus uses a photoreceptor blade to remove toner remaining on the surface of the photoreceptor. Since the photoreceptor blade is in contact with the rotating photoreceptor, the photoreceptor blade is required to have a certain degree of lubricity. The lubricity of the photoreceptor blade is ensured by the lubricant contained in the toner adhering to the photoreceptor blade. For this reason, when the amount of toner adhering to the photoreceptor blade decreases, the photoreceptor blade may be damaged, or streaks may appear along the circumferential direction of the photoreceptor surface due to deterioration of the toner removal performance (cleaning performance) of the photoreceptor blade. Problems such as generation of residual toner (hereinafter sometimes referred to as FD streaks) occur.

In order to suppress the decrease in the amount of toner adhering to the photoreceptor blade, the conventional image forming apparatus controls the timing at which a predetermined number of low-coverage prints continue, the timing at which the print job is completed, or a plurality of images formed by the print job. Toner is supplied to the photoreceptor blade by forming toner patches on the surface of the photoreceptor, such as at times between images.

In recent years, there has been a shortage of toner supplied to the photoreceptor blade due to a decrease in fogging toner (toner that adheres to the non-image areas of the photoreceptor) due to improvements in toner quality, and an improvement in transfer efficiency due to the smaller diameter of the transfer roller. Things are happening frequently. For this reason, it is necessary to form toner patches on the surface of the photoreceptor more frequently (for example, each time an image is formed) to supply toner to the photoreceptor blade.

In general, when a toner patch is supplied to the surface of the photoreceptor, the toner in the toner patch adheres to the transfer roller, and the back side of the paper passing through the transfer roller (the side opposite to the image forming surface) is transferred to the transfer roller. A phenomenon of contamination by the adhering toner (hereinafter sometimes referred to as back contamination) may occur. Back-smearing frequently occurs when the density of the toner patch is too high.

If the transfer roller is cleaned each time a toner patch for supplying toner to the photoreceptor blade is formed, the back side staining can be prevented, but the productivity of the image forming apparatus is lowered. The presence or absence of back staining depends on the density of the toner patch. For this reason, it is required to control the density of the toner patch formed on the surface of the photoreceptor so that the back contamination does not occur even if the transfer roller is not cleaned frequently.

Conventional techniques for forming toner patches are disclosed, for example, in Japanese Patent Application Laid-Open Nos. 2003-100000 and 2000-100000. In Patent Document 1 below, a toner image is formed on a non-image area of a photoreceptor drum based on a patch for forced toner discharge, and when the non-image area of the photoreceptor drum contacts the transfer belt, the polarity of the transfer belt is changed. A technique for switching to the same polarity as the toner is disclosed. With this technology, when the toner patch passes the transfer belt, a reverse bias is applied to the transfer belt during printing to prevent the toner patch from being transferred to the transfer belt and reduce contamination of the secondary transfer section. ing.

Japanese Unexamined Patent Application Publication No. 2002-200003 discloses an image forming apparatus that can operate in a mode of supplying toner to an intermediate transfer belt cleaning blade by forming a toner image on a non-image area of the intermediate transfer belt. In this image forming apparatus, when forming a toner image in a non-image area, the image forming engine generates a toner image of pattern B based on image information processed by the controller (no cleaning is required) based on the required time for each toner image. It is determined whether to form a toner image (toner image) or to form a toner image of pattern C not based on image information (toner image requiring cleaning).

JP 2011-7831 A JP 2015-94857 A

The density of the toner patch varies depending on various factors such as the environment (humidity), toner carrier ratio, distance between the developing device and the photoreceptor, and the like, even if the light amount of the exposure device is constant. For this reason, it has been difficult with the conventional technology to appropriately control the density of the toner patch so that the back side stain does not occur even if the transfer roller is not cleaned frequently.

In the technique disclosed in Japanese Patent Application Laid-Open No. 2002-200002, when the density of the toner patch exceeds a target value, the toner patch adheres to the transfer belt, and the occurrence of back staining cannot be suppressed.

Further, in the technique disclosed in Japanese Patent Application Laid-Open No. 2002-200000, the formation of toner patches in pattern B with a constant toner density is realized by processing with a controller. However, this technique requires a process for creating a toner patch image, resulting in a problem of reduced productivity of the image forming apparatus. Further, when a toner image of pattern C not based on image information is formed, cleaning is required after forming the toner patch, and there is a problem that the productivity of the image forming apparatus is lowered.

SUMMARY OF THE INVENTION The present invention is intended to solve the above problems, and an object of the present invention is to provide an image forming apparatus, an image forming apparatus control method, and an image forming apparatus capable of suppressing the occurrence of contamination on the back side while suppressing a decrease in productivity. is to provide a control program for

An image forming apparatus according to one aspect of the present invention is an image forming apparatus comprising a photoreceptor, a transfer section, and removing means for removing toner on the surface of the photoreceptor, wherein at least the photoreceptor and the transfer section are used to control the formation of a toner image on paper based on a print image under a first forming condition; a toner patch formation control means for forming a toner patch on the surface of the photoreceptor under the second formation conditions determined by the second formation conditions; a transfer voltage control means for controlling the voltage applied to the portion to a voltage at which the toner patch formed on the photoreceptor is not transferred; an intermediate transfer member to which the toner image formed on the photoreceptor is transferred by the transfer portion; density detecting means for detecting the density of the toner patch transferred to the body; and condition correcting means for correcting the second forming conditions after detection by the density detecting means based on the density detected by the density detecting means. If the amount of toner patches indicated by the density detected by the density detection means is higher than the first threshold value, the condition correction means adjusts the amount of toner patches formed on the surface of the photoreceptor after detection by the density detection means. If the density detected by the density detection means is lower than the toner patch amount indicated by the second threshold value lower than the first threshold value, the condition correction means determines that the toner patch amount after detection by the density detection means is lower than the second threshold value. The second threshold is changed according to the primary transfer efficiency, which is the transfer efficiency of the transfer unit, by increasing the amount of toner patch transferred to the surface of the photoreceptor.

An image forming apparatus according to still another aspect of the present invention is an image forming apparatus comprising a photoreceptor, a transfer section, and removing means for removing toner on the surface of the photoreceptor, wherein at least the photoreceptor and the transfer section are used to control the formation of a toner image on paper based on the print image under the first formation conditions, and the first formation conditions when the toner image is formed on the paper by the print control means. a toner patch formation control means for forming a toner patch on the surface of the photoreceptor under the second formation condition determined based on the above; a transfer voltage control means for controlling the voltage applied to the transfer portion to a voltage at which the toner patch formed on the photoreceptor is not transferred; an intermediate transfer member to which the toner image formed on the photoreceptor by the transfer portion is transferred; density detecting means for detecting the density of the toner patch transferred onto the transfer body, the photoreceptor being a plurality of photoreceptors, each of the plurality of photoreceptors corresponding to each of a plurality of colors, and toner patch formation control; Each of the plurality of toner patches formed on each of the plurality of photoreceptors by the means is superimposed and transferred onto the intermediate transfer body, and based on the density detected by the density detection means, after detection by the density detection means. A color number correcting means is further provided for correcting the number of colors of the plurality of toner patches transferred onto the intermediate transfer member in an overlapping manner.

In the above image forming apparatus, preferably, when the amount of toner patches indicated by the density detected by the density detection means is higher than the first threshold value, the color number correction means causes the intermediate transfer member to mutually transfer to the intermediate transfer body after detection by the density detection means. To reduce the number of colors of multiple toner patches that are superimposed and transferred.

In the above image forming apparatus, preferably, when the amount of toner patches indicated by the density detected by the density detection means is higher than the first threshold value, the color number correction means selects a color having a low priority among the plurality of photoreceptors. Do not form toner patches on the corresponding photoreceptor surface.

An image forming apparatus according to still another aspect of the present invention is an image forming apparatus comprising a photoreceptor, a transfer section, and removing means for removing toner on the surface of the photoreceptor, wherein at least the photoreceptor and the transfer section are used to control the formation of a toner image on paper based on the print image under the first formation conditions, and the first formation conditions when the toner image is formed on the paper by the print control means. a toner patch formation control means for forming a toner patch on the surface of the photoreceptor under the second formation condition determined based on the above; a transfer voltage control means for controlling the voltage applied to the transfer portion to a voltage at which the toner patch formed on the photoreceptor is not transferred; an intermediate transfer member to which the toner image formed on the photoreceptor by the transfer portion is transferred; density detecting means for detecting the density of the toner patch transferred onto the transfer body, the photoreceptor being a plurality of photoreceptors, each of the plurality of photoreceptors corresponding to each of a plurality of colors, and toner patch formation control; Each of the plurality of toner patches formed on each of the plurality of photoreceptors by the means is superimposed and transferred onto the intermediate transfer body, and based on the density detected by the density detection means, after detection by the density detection means. A position of at least one toner patch among the plurality of toner patches transferred to the intermediate transfer member, wherein at least one toner patch among the plurality of toner patches formed between toner images of the plurality of print images. It further comprises position correcting means for correcting the position of the .

In the above image forming apparatus, preferably, when the amount of toner patches indicated by the density detected by the density detection means is higher than the first threshold value, the position correction means selects one of the plurality of toner patches to be transferred onto the intermediate transfer body. The position of at least one toner patch, wherein the position of at least one toner patch among a plurality of toner patches formed between each toner image of a plurality of print images, is the position of the other toner patch among the plurality of toner patches. Move away from the patch position.

The image forming apparatus preferably further includes a secondary transfer section for transferring the toner image based on the printed image from the intermediate transfer member to the paper, and the transfer voltage control means controls the toner patch to pass through a region facing the secondary transfer section. At this time, the voltage applied to the secondary transfer portion is further controlled to a voltage at which the toner patch formed on the intermediate transfer member is not transferred.

In the above image forming apparatus, preferably, the voltage at which the toner patch formed on the intermediate transfer member is not transferred is a voltage lower than the voltage for forming the toner image of the print image, zero, or the toner patch formed on the intermediate transfer member. is the same potential as
Preferably, in the image forming apparatus, the first forming condition includes a developing bias when forming a toner image based on a print image.
Preferably, in the image forming apparatus, the first forming condition includes a laser light amount when forming a toner image based on a print image.
In the above image forming apparatus, preferably, the first forming condition includes the rotational speed of the photoreceptor, the color of the toner image formed on the photoreceptor, the degree of wear of the photoreceptor, the environment of the image forming apparatus, and the resolution of the printed image. including at least one of the parameters.
The image forming apparatus preferably further includes a storage device that stores a table showing the relationship between at least one of the parameters and the second forming conditions.
Preferably, in the image forming apparatus, the first forming condition is a condition determined by image stabilization processing performed by the image forming apparatus.
Preferably, in the above image forming apparatus, the first forming condition is a condition determined based on at least one of the environment of the image forming apparatus and the degree of consumption of consumables of the image forming apparatus.
The image forming apparatus preferably further comprises a laser beam irradiation means for irradiating a laser beam for forming an electrostatic latent image on the surface of the photoreceptor to form a toner image, and the second forming condition is the laser beam. It is the amount of laser light emitted by the irradiation means.
The image forming apparatus preferably includes a charging section to which a charging bias is applied to charge the surface of the photoreceptor, and a developing section to which a developing bias is applied and develops the electrostatic latent image formed on the surface of the photoreceptor. In addition, the second forming condition is the difference between the charging bias and the developing bias.
Preferably, in the image forming apparatus, the toner patch formation control means applies a charging bias or a developing bias having a magnitude calculated based on the difference.

In the above image forming apparatus, preferably, the voltage at which the toner patch formed on the photoreceptor is not transferred is a voltage lower than the voltage for forming the toner image of the print image, zero, or the same voltage as the toner patch formed on the photoreceptor. It is the voltage that becomes the electric potential.

In the above image forming apparatus, preferably, the toner patch formation is determined based on at least one of the degree of wear of the photoreceptor, the environment of the image forming apparatus, and the total number of toner patches formed since the start of the image forming apparatus. It further comprises implementation determining means for determining necessity.

In the above image forming apparatus, the timing of forming the toner patches is preferably determined based on at least one of the degree of wear of the photoreceptor, the environment of the image forming apparatus, and the number of toner patches formed from the start of the print job. A timing determining means is further provided.

The image forming apparatus preferably further includes length determining means for determining the length of the toner patch based on at least one of the degree of wear of the photoreceptor and the environment of the image forming apparatus.

A control method for an image forming apparatus according to another aspect of the present invention includes a photoreceptor, a transfer section, a removing means for removing toner on the surface of the photoreceptor, and a toner image formed on the photoreceptor by the transfer section. A control method for an image forming apparatus having an intermediate transfer member, the control method forming a toner image based on a print image on a sheet under first forming conditions using at least a photoreceptor and a transfer unit. and a second forming condition determined based on the first forming condition when forming a toner image on a sheet in the print controlling step to form a toner patch on the surface of the photoreceptor. In the toner patch formation control step, when the toner patch formed on the surface of the photoreceptor passes through the portion facing the transfer portion, the voltage applied to the transfer portion is changed to a voltage at which the toner patch formed on the photoreceptor is not transferred. a transfer voltage control step for controlling; a density detection step for detecting the density of the toner patch transferred to the intermediate transfer body; and a condition correction step for correcting the condition, wherein if the amount of toner patches indicated by the density detected in the density detection step is higher than the first threshold value, the condition correction step corrects the photoreceptor after detection by the density detection step. The amount of toner patches formed on the surface is reduced, and if the amount of toner patches indicated by the density detected in the density detection step is lower than a second threshold lower than the first threshold, condition correction is performed. In the step, the amount of toner patches transferred to the surface of the photoreceptor after detection by the density detection step is increased, and the second threshold is changed according to the primary transfer efficiency, which is the transfer efficiency of the transfer unit.
A control method for an image forming apparatus according to still another aspect of the present invention includes a photoreceptor, a transfer section, removing means for removing toner on the surface of the photoreceptor, and a toner image formed on the photoreceptor by the transfer section. A control method for an image forming apparatus having an intermediate transfer member to be transferred, wherein the control method uses at least a photoreceptor and a transfer unit to form a toner image based on a print image on a sheet under first forming conditions. A toner patch is formed on the surface of the photoreceptor in a print control step for controlling formation and a second formation condition determined based on the first formation condition when forming a toner image on paper in the print control step. and a voltage applied to the transfer section when the toner patch formed on the surface of the photoreceptor passes through a portion facing the transfer section, and a voltage at which the toner patch formed on the photoreceptor is not transferred. and a density detection step of detecting the density of the toner patch transferred to the intermediate transfer member. , each of the plurality of toner patches formed on each of the plurality of photoreceptors in the toner patch formation control step is superimposed and transferred onto the intermediate transfer member, and the density detected in the density detection step is obtained. Based on this, the method further includes a color number correction step of correcting the number of colors of the plurality of toner patches that are superimposed and transferred onto the intermediate transfer member after detection by the density detection step.
A control method for an image forming apparatus according to still another aspect of the present invention includes a photoreceptor, a transfer section, removing means for removing toner on the surface of the photoreceptor, and a toner image formed on the photoreceptor by the transfer section. A control method for an image forming apparatus having an intermediate transfer member to be transferred, wherein the control method uses at least a photoreceptor and a transfer unit to form a toner image based on a print image on a sheet under first forming conditions. A toner patch is formed on the surface of the photoreceptor in a print control step for controlling formation and a second formation condition determined based on the first formation condition when forming a toner image on paper in the print control step. and a voltage applied to the transfer section when the toner patch formed on the surface of the photoreceptor passes through a portion facing the transfer section, and a voltage at which the toner patch formed on the photoreceptor is not transferred. and a density detection step of detecting the density of the toner patch transferred to the intermediate transfer member. , each of the plurality of toner patches formed on each of the plurality of photoreceptors in the toner patch formation control step is superimposed and transferred onto the intermediate transfer member, and the density detected in the density detection step is obtained. position of at least one toner patch among a plurality of toner patches transferred to the intermediate transfer member after detection by the density detection step, and a plurality of toner patches formed between toner images of a plurality of print images; and a position correction step of correcting the position of at least one of the toner patches.

A control program for an image forming apparatus according to still another aspect of the present invention includes a photoreceptor, a transfer section, removing means for removing toner on the surface of the photoreceptor, and a toner image formed on the photoreceptor by the transfer section. A control program for an image forming apparatus having an intermediate transfer member to be transferred, the control program forming a toner image based on a print image on a sheet of paper under first forming conditions using at least a photoreceptor and a transfer unit. A toner patch is formed on the surface of the photoreceptor in a print control step for controlling formation and a second formation condition determined based on the first formation condition when forming a toner image on paper in the print control step. and a voltage applied to the transfer section when the toner patch formed on the surface of the photoreceptor passes through a portion facing the transfer section, and a voltage at which the toner patch formed on the photoreceptor is not transferred. a density detection step of detecting the density of the toner patch transferred to the intermediate transfer body; and a second step after detection by the density detection step based on the density detected in the density detection step. and a condition correction step for correcting the forming conditions, and if the amount of toner patches indicated by the density detected in the density detection step is higher than the first threshold value, the condition correction step is performed after detection by the density detection step. The amount of toner patches formed on the surface of the photoreceptor is reduced, and the amount of toner patches indicated by the density detected in the density detection step is lower than the second threshold, which is lower than the first threshold. In this case, in the condition correction step, the amount of toner patches transferred to the surface of the photoreceptor after detection by the density detection step is increased, and the second threshold is changed according to the primary transfer efficiency, which is the transfer efficiency of the transfer unit. be done.
A control program for an image forming apparatus according to still another aspect of the present invention includes a photoreceptor, a transfer section, removing means for removing toner on the surface of the photoreceptor, and a toner image formed on the photoreceptor by the transfer section. A control program for an image forming apparatus having an intermediate transfer member to be transferred, the control program forming a toner image based on a print image on a sheet of paper under first forming conditions using at least a photoreceptor and a transfer unit. A toner patch is formed on the surface of the photoreceptor in a print control step for controlling formation and a second formation condition determined based on the first formation condition when forming a toner image on paper in the print control step. and a voltage applied to the transfer section when the toner patch formed on the surface of the photoreceptor passes through a portion facing the transfer section, and a voltage at which the toner patch formed on the photoreceptor is not transferred. and a density detection step of detecting the density of the toner patch transferred to the intermediate transfer member. Each of the plurality of toner patches corresponding to each color and formed on each of the plurality of photoreceptors in the toner patch formation control step is superimposed and transferred onto the intermediate transfer member and detected in the density detection step. Based on the determined density, the computer is further caused to execute a color number correction step for correcting the number of colors of the plurality of toner patches to be superimposed and transferred onto the intermediate transfer member after detection by the density detection step.
A control program for an image forming apparatus according to still another aspect of the present invention includes a photoreceptor, a transfer section, removing means for removing toner on the surface of the photoreceptor, and a toner image formed on the photoreceptor by the transfer section. A control program for an image forming apparatus having an intermediate transfer member to be transferred, the control program forming a toner image based on a print image on a sheet of paper under first forming conditions using at least a photoreceptor and a transfer unit. A toner patch is formed on the surface of the photoreceptor in a print control step for controlling formation and a second formation condition determined based on the first formation condition when forming a toner image on paper in the print control step. and a voltage applied to the transfer section when the toner patch formed on the surface of the photoreceptor passes through a portion facing the transfer section, and a voltage at which the toner patch formed on the photoreceptor is not transferred. and a density detection step of detecting the density of the toner patch transferred to the intermediate transfer member. Each of the plurality of toner patches corresponding to each color and formed on each of the plurality of photoreceptors in the toner patch formation control step is superimposed and transferred onto the intermediate transfer member and detected in the density detection step. position of at least one toner patch among a plurality of toner patches transferred to the intermediate transfer member after detection by the density detection step based on the determined density, and formed between toner images of the plurality of print images; The computer is further caused to perform a position correction step of correcting the position of at least one of the plurality of toner patches applied.

An object of the present invention is to provide an image forming apparatus, a control method for the image forming apparatus, and a control program for the image forming apparatus that can suppress the occurrence of back stains while suppressing a decrease in productivity.

1 is a cross-sectional view schematically showing the configuration of an image forming apparatus 1 according to a first embodiment of the invention; FIG. 1 is a block diagram showing the configuration of an image forming apparatus 1 according to a first embodiment of the invention; FIG. FIG. 2 is a diagram schematically showing a toner image formed on the surface of photoreceptor 22 in the first embodiment of the present invention; FIG. 3 is a time variation of light emission of exposure unit 21 and voltage applied to each of primary transfer unit 27 and secondary transfer unit 29 when image forming apparatus 1 executes a print job in the first embodiment of the present invention; It is a figure which shows. 5 is a diagram schematically showing an environment value table stored in a ROM 51b in the first embodiment of the invention; FIG. 5 is a diagram schematically showing a first part of a reference light amount table stored in a ROM 51b in the first embodiment of the invention; FIG. It is a figure which shows typically the 2nd part of the reference|standard light quantity table which ROM51b memorize|stores in the 1st Embodiment of this invention. FIG. 5 is a diagram schematically showing a light intensity correction coefficient table according to development bias, stored in a ROM 51b in the first embodiment of the present invention; FIG. 4 is a diagram schematically showing a light intensity correction coefficient table according to laser light intensity, stored in a ROM 51b in the first embodiment of the present invention; 4 is a flow chart showing the operation of the image forming apparatus 1 according to the first embodiment of the present invention; FIG. 11 is a subroutine of toner patch processing (S5) of FIG. 10 in the first embodiment of the present invention; FIG. Voltage applied to each of the charging unit 23, the developing unit 24, the primary transfer unit 27, and the secondary transfer unit 29 when the image forming apparatus 1 executes a print job in the second embodiment of the present invention. It is a figure which shows an example of a time change. Voltage applied to each of the charging unit 23, the developing unit 24, the primary transfer unit 27, and the secondary transfer unit 29 when the image forming apparatus 1 executes a print job in the second embodiment of the present invention. FIG. 10 is a diagram showing another example of time change; FIG. 9 is a diagram schematically showing a first part of a reference fogging margin table stored in a ROM 51b in the second embodiment of the invention; FIG. 9 is a diagram schematically showing a second part of a reference fogging margin table stored in a ROM 51b in the second embodiment of the invention; FIG. 9 is a diagram schematically showing a fogging margin correction coefficient table corresponding to developing bias, stored in a ROM 51b in the second embodiment of the present invention; FIG. 10 is a diagram schematically showing a fog margin correction coefficient table corresponding to the amount of laser light stored in a ROM 51b in the second embodiment of the present invention; This is a subroutine of toner patch processing (S5) in FIG. 10 according to the second embodiment of the present invention, and is a subroutine of toner patch processing in the case of controlling charging bias when forming a toner patch. This is a subroutine for toner patch processing (S5) in FIG. 10 according to the second embodiment of the present invention, and is a subroutine for toner patch processing when controlling the developing bias when forming a toner patch. FIG. 13 is a diagram showing the relationship between the amount of toner patches on the surface of the intermediate transfer member 28, the back side stain threshold TH1, and the FD streak threshold TH2 according to the third embodiment of the present invention; FIG. 11 is a diagram schematically showing a primary transfer efficiency table stored in a ROM 51b in the third embodiment of the invention; FIG. FIG. 11 is a diagram schematically showing an FD muscle threshold table stored in a ROM 51b in the third embodiment of the present invention; FIG. FIG. 11 is a subroutine of toner patch density detection processing (S7) of FIG. 10 in the third embodiment of the present invention; FIG. 8 is a diagram showing the relationship between the number of colors of toner patches superimposed and transferred on the surface of the intermediate transfer body 28 and the amount of toner patches on the surface of the intermediate transfer body 28 in the third embodiment of the present invention; FIG. . FIG. 11 is a subroutine of the toner patch density detection process (S7) of FIG. 10 in the first modified example of the third embodiment of the invention; FIG. FIG. 10 is a diagram schematically showing a toner image formed on the surface of an intermediate transfer member 28 in a second modified example of the third embodiment of the invention; FIG. 11 is a subroutine of the toner patch density detection process (S7) of FIG. 10 in the second modified example of the third embodiment of the invention; FIG. FIG. 11 is a diagram schematically showing a patch formation necessity table stored in a ROM 51b in another embodiment of the present invention; FIG. 11 is a diagram schematically showing a patch formation timing table stored in a ROM 51b in another embodiment of the invention; FIG. 10 is a diagram schematically showing a patch length table stored in a ROM 51b in another embodiment of the invention;

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

In the following embodiments, a case where the image forming apparatus is an MFP will be described. The image forming apparatus may be an MFP, a facsimile machine, a copier, a printer, or the like, and may be monochrome or color.

[First embodiment]

(Configuration of image forming apparatus)

First, the configuration of the image forming apparatus according to this embodiment will be described.

FIG. 1 is a cross-sectional view schematically showing the configuration of an image forming apparatus 1 according to the first embodiment of the invention.

Referring to FIG. 1, image forming apparatus 1 (an example of image forming apparatus) in the present embodiment is an MFP, and mainly includes sheet conveying section 10, toner image forming section 20, and fixing device 30. ing.

The paper transport section 10 transports the paper along a transport path (transport direction) TR. The paper transport section 10 includes a paper feed tray 11 , paper feed rollers 12 , registration rollers 13 , paper discharge rollers 14 , and a paper discharge tray 15 . The paper feed tray 11 accommodates paper for forming images. A plurality of paper feed trays 11 may be provided. The paper feed roller 12 is provided between the paper feed tray 11 and the transport path TR. The registration roller 13 is provided upstream of the secondary transfer portion 29 in the transport path TR. The paper discharge roller 14 is provided at the most downstream portion of the transport path TR. The paper discharge tray 15 is provided at the top of the image forming apparatus main body 1a.

The toner image forming unit 20 synthesizes four-color images of Y (yellow), M (magenta), C (cyan), and K (black) by a so-called tandem method, and forms a toner image on the conveyed paper. . The toner image forming section 20 includes an image forming unit 20A for each color of YMCK, an exposure section 21 (an example of laser light irradiation means), a primary transfer section 27 for each color of YMCK (an example of a transfer section), and an intermediate transfer member 28. (an example of an intermediate transfer member) and a secondary transfer section 29 (an example of a secondary transfer section).

The YMCK color image forming units 20A are provided in this order between the exposure unit 21 and the intermediate transfer member 28 along the rotation direction of the intermediate transfer member 28 indicated by the arrow β. The YMCK color image forming unit 20A includes a photoconductor 22 (an example of a photoconductor), a charging section 23 (an example of a charging section), a developing section 24 (an example of a developing section), an eraser section 25, and a photoconductor blade. 26 (an example of removal means). The photosensitive member 22 is rotationally driven in the direction indicated by the arrow α in FIG. Around the photoconductor 22, a charging section 23, a developing section 24, an eraser section 25, and a photoconductor blade 26 are provided in this order along the direction indicated by the arrow α.

The intermediate transfer member 28 is provided above the YMCK color image forming units 20A. The intermediate transfer member 28 is composed of an endless belt and is stretched over a rotating roller 28a. The intermediate transfer member 28 is rotationally driven in the direction indicated by the arrow β in FIG. Each primary transfer portion 27 for each color of YMCK faces each photoreceptor 22 with an intermediate transfer member 28 interposed therebetween. The secondary transfer portion 29 is in contact with the intermediate transfer body 28 on the transport path TR. Photoreceptor 22 is in contact with the surface of intermediate transfer member 28 .

The fixing device 30 fixes the toner image on the paper by conveying the paper along the conveying path TR while gripping the paper on which the toner image is formed by the fixing nip.

The image forming apparatus 1 rotates the photoreceptor 22 and uniformly charges the surface of the photoreceptor 22 by the charging unit 23 . The image forming apparatus 1 exposes the surface of the charged photoreceptor 22 to laser light emitted from the exposure unit 21 according to the image forming information, and deposits static electricity on the surface of the photoreceptor 22 that forms a toner image. Forms an electrostatic latent image.

Next, the image forming apparatus 1 supplies toner from the developing unit 24 to the photoreceptor 22 on which the electrostatic latent image is formed, and develops the photoreceptor 22 to form a toner image on the surface of the photoreceptor 22 .

Next, the image forming apparatus 1 sequentially transfers the toner image formed on the surface of the photoreceptor 22 onto the surface of the intermediate transfer body 28 using the primary transfer unit 27 at the contact position between the photoreceptor 22 and the intermediate transfer body 28 . Transcribe (primary transcription). In the case of a full-color image, each color of the toner image transferred to the intermediate transfer member 28 is superimposed each time it passes through each image forming unit 20A, and finally a full-color toner image is formed on the intermediate transfer member 28 . The image forming apparatus 1 removes the electrons remaining on the surface of the photoreceptor 22 after the primary transfer by the eraser unit 25, and removes the toner remaining on the surface of the photoreceptor 22 without being transferred to the intermediate transfer member 28 by a photoreceptor blade. 26.

Subsequently, the image forming apparatus 1 conveys the toner image formed on the surface of the intermediate transfer member 28 to a position facing the secondary transfer portion 29 by the rotating roller 28a.

On the other hand, the image forming apparatus 1 feeds the sheets accommodated in the paper feed tray 11 one by one by the paper feed roller 12, and the registration roller 13 transfers the intermediate transfer body 28 and the secondary transfer portion 29 at a predetermined timing. lead between Then, the image forming apparatus 1 transfers the toner image formed on the surface of the intermediate transfer member 28 onto a sheet by the secondary transfer portion 29 .

The image forming apparatus 1 guides the sheet onto which the toner image has been transferred to the fixing device 30, and the fixing device 30 fixes the toner image onto the sheet. After that, the image forming apparatus 1 discharges the paper on which the toner image is fixed to the paper discharge tray 15 by the paper discharge roller 14 .

FIG. 2 is a block diagram showing the configuration of the image forming apparatus 1 according to the first embodiment of the invention.

Referring to FIG. 2 , image forming apparatus 1 includes engine control unit 51 , MFP controller 52 (an example of print control means), environment sensor 53 , life management unit 54 , and IDC (Image Density Control) sensor 55 . and 56 (an example of density detection means).

The charging section 23 , the developing section 24 , the primary transfer section 27 , and the secondary transfer section 29 are members that receive power supply from a high voltage power source (not shown), and constitute a high voltage section 57 .

Under the control of the MFP controller 52, the engine control unit 51 controls the operations of members (print engine) involved in the printing operation in the image forming apparatus 1, such as the exposure unit 21, the eraser unit 25, and the high pressure unit 57. . The engine control unit 51 includes an engine control CPU (Central Processing Unit) 51a (toner patch formation control means, transfer voltage control means, condition correction means, color number correction means, position correction means, execution determination means, an example of timing determination means and length determination means), a ROM (Read Only Memory) 51b (an example of a storage device) for storing various information such as a control program, and a RAM (Random Access) for temporarily storing various information. Memory) 51c.

The MFP controller 52 controls the entire image forming apparatus 1 . In particular, the MFP controller 52 transmits exposure information corresponding to the print image included in the print job to the exposure section 21 . The exposure unit 21 draws an electrostatic latent image on the surface of the photoreceptor 22 based on exposure information received from the MFP controller 52 . The MFP controller 52 includes a CPU, ROM, RAM, and the like.

The environment sensor 53 detects the environment of the image forming apparatus 1 (here, the absolute humidity value inside the image forming apparatus 1) and outputs it to the engine control section 51. FIG.

Lifespan management unit 54 detects the degree of wear of consumables of image forming apparatus 1 , such as the cumulative number of rotations of photoreceptor 22 , and outputs it to engine control unit 51 .

The IDC sensor 55 detects the density of the toner image remaining on the surface of the photoreceptor 22 without being transferred, and outputs it to the engine control section 51 .

The IDC sensor 56 detects the density of the toner image formed on the surface of the intermediate transfer body 28 and outputs it to the engine control section 51 .

(Basic Operation of Image Forming Apparatus)

Next, a basic operation of the image forming apparatus 1 according to this embodiment will be described.

FIG. 3 is a diagram schematically showing a toner image formed on the surface of photoreceptor 22 in the first embodiment of the invention.

Referring to FIG. 3, MFP controller 52 generates data of a plurality of (here, three) print images IM1, IM2, and IM3 included in the print job upon receiving an instruction to execute the print job. MFP controller 52 controls engine control unit 51 to sequentially form toner images based on print images IM1, IM2, and IM3 on the surface of photoreceptor 22 at predetermined intervals L3 under predetermined forming conditions.

When forming the toner images of the plurality of print images IM1, IM2, and IM3 in order on the surface of the photoreceptor 22, the engine control unit 51 controls the toner image of each of the plurality of print images IM1, IM2, and IM3 on the surface of the photoreceptor 22. A toner patch PT is formed at least one of positions between the toner images and positions behind the toner image of the last print image IM3 in the print job. Here, the position between the toner images of the print image IM1 and the toner image of the print image IM2, the position between the toner image of the print image IM2 and the toner image of the print image IM3, and the toner image of the last print image IM3 A toner patch PT is formed at each position behind the .

Note that the distance L1 is the distance from the rotation start position of the photosensitive member 22 at the start of the print job to the toner patch formation start position, or the distance from the previous toner patch formation end position to the next toner patch formation start position. is. The length L2 is the length of the toner patch PT along the circumferential direction of the photoreceptor 22 . In order to supply the toner to the required area on the photoreceptor blade 26, the toner patch PT is preferably formed with the same width as the full width of the image forming area in the main scanning direction.

The engine control unit 51 controls the print engine under the control of the MFP controller 52 when forming the toner images of the print images IM1, IM2, and IM3. On the other hand, when forming the toner patch PT, the engine control unit 51 controls the print engine without the control of the MFP controller 52 (forced light emission of the exposure unit 21, etc.).

FIG. 4 shows the light emission of the exposure unit 21 and the light applied to each of the primary transfer unit 27 and the secondary transfer unit 29 when the image forming apparatus 1 executes a print job in the first embodiment of the present invention. It is a figure which shows the time change of a voltage.

Referring to FIG. 4, at the timing when the areas on the surface of photoreceptor 22 where the electrostatic latent images of print images IM1, IM2, and IM3 are formed pass through the irradiation area of the laser light, engine control unit 51 Under the control of MFP controller 52, exposure unit 21 emits laser light to form electrostatic latent images of print images IM1, IM2, and IM3.

When a print job is started, engine control unit 51 applies a voltage corresponding to an output value during printing to each of charging unit 23 and developing unit 24 under the control of MFP controller 52 (charging unit 23, The printing output values of the developing section 24, the primary transfer section 27, and the secondary transfer section 29 are mutually different values). As a result, toner images of the print images IM1, IM2, and IM3 are formed on the surface of the photoreceptor 22 . The toner images of the print images IM1, IM2, and IM3 are transferred onto the intermediate transfer member 28 and sequentially transferred onto a sheet of paper passing between the intermediate transfer member 28 and the secondary transfer portion 29 .

The conditions for forming the print images IM1, IM2, and IM3 (the output values at the time of printing of the charging unit 23, the developing unit 24, the primary transfer unit 27, and the secondary transfer unit 29, etc.) are determined by executing the print job of the image forming apparatus 1. The condition may be determined by image stabilization processing performed at a timing different from the timing at which the It may be a determined condition.

On the other hand, at the timing when the area forming each toner patch PT on the surface of the photoreceptor 22 passes through the irradiation area of the laser beam, the engine control unit 51 causes the laser beam to be emitted from the exposure unit 21 without control from the MFP controller 52. is irradiated (forced light emission of the exposure unit 21) to form an electrostatic latent image of each of the plurality of toner patches PT.

At the timing when the toner image of the toner patch PT formed on the surface of the photoreceptor 22 passes through the area facing the primary transfer portion 27 , the engine control portion 51 transfers the image to the primary transfer portion 27 without control from the MFP controller 52 . The applied voltage is controlled to a voltage at which the toner patch PT formed on the photoreceptor 22 is not transferred. As a result, most of the toner in the toner patch PT formed on the surface of the photoreceptor 22 is supplied to the photoreceptor blade 26 and is less likely to adhere to the intermediate transfer body 28 .

The voltage at which the toner patch formed on the photoreceptor 22 is not transferred is a voltage that is lower than the voltage at the time of forming the toner image of the print image, zero, or a voltage that has the same potential as the toner patch formed on the photoreceptor 22. .

At the timing when the toner image of the toner patch PT formed on the surface of the intermediate transfer member 28 passes through the area facing the secondary transfer portion 29, the engine control portion 51 performs the secondary transfer without control from the MFP controller 52. The voltage applied to the portion 29 is controlled to a voltage at which the toner patch PT formed on the intermediate transfer member 28 is not transferred. As a result, the toner in the toner patch PT formed on the surface of the intermediate transfer body 28 stays on the intermediate transfer body 28 and is less likely to adhere to the secondary transfer portion 29 .

The voltage at which the toner patch formed on the intermediate transfer member 28 is not transferred is a voltage lower than the voltage for forming the toner image of the print image, zero, or a voltage equal to the potential of the toner patch formed on the intermediate transfer member 28. is.

When the toner patch PT is supplied to the photosensitive blade 26, the engine control unit 51 sets the toner patch PT forming condition (second forming condition) determined based on the print image forming condition (an example of the first forming condition). Example of condition), the toner patch PT is formed on the surface of the photoreceptor 22 .

In the present embodiment, the amount of laser light irradiated by the exposure unit 21 when forming the toner patch is determined as the toner patch forming condition. When forming the toner patch, the determined amount of laser light is irradiated.

(Method for Determining Conditions for Forming Toner Patches)

Next, a method for determining the toner patch forming conditions according to the present embodiment will be described.

The engine control unit 51 determines the environmental value based on the absolute humidity value acquired from the environmental sensor 53 using the environmental value table when determining the toner patch forming conditions. Next, the engine control unit 51 determines the reference light intensity using the reference light intensity table. The reference light amount is the resolution of the printed image, the peripheral speed (rotational speed) of the photoreceptor 22, the color of the toner image formed on the photoreceptor 22, and the cumulative number of rotations of the photoreceptor 22 obtained from the life management unit 54. , and environmental values determined using the environmental table.

FIG. 5 is a diagram schematically showing an environment value table stored in the ROM 51b according to the first embodiment of the invention.

Referring to FIG. 5, the environmental value table is a table describing the relationship between the environment of image forming apparatus 1 (here, the absolute humidity value within image forming apparatus 1) and the environmental values. In this environment value table, the environment value is "1" when the absolute humidity value X is less than 10, and the environment value is "2" when the absolute humidity value X is 10 or more and less than 20. If the absolute humidity value X is 20 or more, it is defined that the environmental value is "3".

6 and 7 are diagrams schematically showing reference light amount tables stored in the ROM 51b in the first embodiment of the present invention.

6 and 7, the reference light amount table includes the resolution of the printed image, the circumferential speed of the photoreceptor 22, the color of the toner image formed on the photoreceptor 22, the color of the toner image formed on the photoreceptor 22, and the and the environmental value determined using the environmental table, and the reference light amount (mJ/m ² ), which is the reference value of the laser light amount irradiated by the exposure unit 21 when forming the toner patch. It is a table. The reference light amount table defines a reference light amount for supplying the photoreceptor blade 26 with a toner amount that does not cause FD streaks or back stains.

Specifically, FIGS. 6 and 7 show four reference light quantity tables. When the resolution of the print image is 600 dpi, the reference light intensity table of FIG. 6 is referred to, and when the resolution of the print image is 1200 dpi, the reference light intensity table of FIG. 7 is referred. When the peripheral speed (rotational speed) of the photoreceptor is 200 mm/s, the reference light quantity table described as "peripheral speed of photoreceptor: 200 mm/s" in FIG. 6(a) or FIG. 7(a) is If the peripheral speed of the photoreceptor is 100 mm/s, refer to the reference light quantity table described as "peripheral speed of photoreceptor: 100 mm/s" in FIG. 6(b) or 7(b). be done.

In one reference light quantity table, the color of the toner image formed on the photoreceptor and the cumulative number of rotations of the photoreceptor are divided in the vertical direction. The color of the toner image formed on the photoreceptor is classified into four categories of KYMC, and the cumulative number of revolutions of the photoreceptor is classified into three categories of less than 300 krot, 300 krot to less than 600 krot, and 600 krot or more. In one reference light intensity table, environmental values are divided into values 1 to 3 in the horizontal direction.

As an example, the resolution of the printed image is 600 dpi, the peripheral speed of the photoreceptor is 200 mm/s, the color of the toner image formed on the photoreceptor is K, and the cumulative number of rotations of the photoreceptor is 300 krot or more and less than 600 krot. and when the environmental value is "2", the reference light amount is determined to be "60" (mJ/m ² ).

The print image forming conditions used to determine the toner patch forming conditions are the rotation speed of the photoreceptor 22, the color of the toner image formed on the photoreceptor 22, the degree of wear of the photoreceptor 22, the image forming apparatus 1 and the resolution of the printed image.

The engine control unit 51 may irradiate the determined reference amount of laser light when forming the toner patch. Further, the engine control unit 51 may correct the determined reference light amount based on at least one of the developing bias and the laser light amount when forming the toner image based on the print image. In this case, when the toner patch is formed, the corrected amount of laser light is irradiated.

Next, a method for correcting the reference amount of light in this embodiment will be described.

FIG. 8 is a diagram schematically showing a light amount correction coefficient table corresponding to the development bias stored in the ROM 51b in the first embodiment of the invention.

Referring to FIG. 8, the light amount correction coefficient table corresponding to the development bias shows the relationship between the development bias (voltage applied to the developing unit 24) and the light amount correction coefficient when forming a toner image based on a print image. It is the described table. This light amount correction coefficient table is for correcting the reference light amount determined using the reference light amount table according to the development characteristics. In this light quantity correction coefficient table, the colors of the toner image formed on the photoreceptor are divided into four KYMC in the vertical direction. Further, in this light quantity correction coefficient table, the developing bias is divided into three groups in the horizontal direction: -250V or more, -500V or more and less than -250V, and less than -500V.

As an example, when the color of the toner image formed on the photoreceptor is K and the development bias when forming the toner image based on the printed image is less than -500 V, the light amount correction coefficient is "1.05". is determined by

The engine control unit 51 corrects (calculates) the amount of laser light when forming the toner patch using the following formula (1).

Amount of laser light (mJ/m ² ) for forming a toner patch=reference amount of light (mJ/m ² )×light amount correction coefficient (1)

FIG. 9 is a diagram schematically showing a light amount correction coefficient table according to the laser light amount, stored in the ROM 51b in the first embodiment of the present invention.

Referring to FIG. 9, the light amount correction coefficient table corresponding to the laser light amount shows the relationship between the laser light amount (the laser light amount irradiated by the exposure unit 21) and the light amount correction coefficient when forming a toner image based on the print image. It is the described table. This light amount correction coefficient table is for correcting the reference light amount determined using the reference light amount table according to the exposure characteristics. In this light quantity correction coefficient table, the colors of the toner image formed on the photoreceptor are divided into four KYMC in the vertical direction. Further, in this light amount correction coefficient table, in the horizontal direction, the laser light amount is less than 1.0 mJ/m ² , 1.0 mJ/m ² or more and less than 3.0 mJ/m ² , and 3.0 mJ/m ² or more. divided into two.

As an example, when the color of the toner image formed on the photoreceptor is K and the amount of laser light when forming the toner image based on the printed image is less than 1.0 mJ/m ² , the light amount correction coefficient is "0.9".

The engine control unit 51 uses Equation (1) to correct (calculate) the amount of laser light when forming the toner patch.

By using the amount of laser light determined by the above-described method when forming a toner patch, the density of the toner patch PT can be appropriately set based on the print image forming conditions while supplying the toner to the photosensitive blade 26 . , contamination of the secondary transfer portion 29 by the toner of the toner patch is suppressed.

(flowchart)

Next, a flowchart of the operation of the image forming apparatus according to this embodiment will be described.

FIG. 10 is a flow chart showing the operation of the image forming apparatus 1 according to the first embodiment of the invention.

Referring to FIG. 10, engine control CPU 51a determines whether or not the print operation of the print job has started (S1). The engine control CPU 51a repeats the process of step S1 until it determines that the printing operation of the print job has started.

When it is determined in step S1 that the printing operation of the print job has started (S1), the engine control CPU 51a determines whether it is time to form a toner patch (S3).

If it is determined in step S3 that it is not the time to form a toner patch (NO in S3), the engine control CPU 51a proceeds to the process of step S7.

If it is determined in step S3 that it is time to form a toner patch (YES in S3), the engine control CPU 51a performs a toner patch process (S5), and proceeds to step S7.

In step S7, the engine control CPU 51a performs a toner patch density detection process (S7), which will be described later, as necessary, and determines whether or not the printing operation of the print job has ended (S9).

When it is determined in step S9 that the printing operation of the print job is not finished (NO in S9), the engine control CPU 51a proceeds to the process of step S3.

If it is determined in step S9 that the printing operation of the print job has ended (YES in S9), the engine control CPU 51a ends the process.

FIG. 11 is a subroutine of toner patch processing (S5) of FIG. 10 in the first embodiment of the invention.

Referring to FIG. 11, in the toner patch process, engine control CPU 51a determines the amount of laser light for forming a toner patch (S21), and starts forced light emission of exposure unit 21 (S23). Next, the engine control CPU 51a determines whether or not the electrostatic latent image corresponding to the toner patch of the target length has been formed on the surface of the photoreceptor 22 (S25). The engine control CPU 51a repeats the process of step S25 until it determines that the electrostatic latent image corresponding to the toner patch of the target length has been formed on the surface of the photoreceptor 22. FIG.

If it is determined in step S25 that an electrostatic latent image corresponding to the toner patch of the target length has been formed on the surface of the photoreceptor 22 (YES in S25), the engine control CPU 51a terminates the forced light emission of the exposure unit 21. (S27). Next, the engine control CPU 51a develops the electrostatic latent image to form a toner patch, and determines whether the toner patch formed on the surface of the photoreceptor 22 has reached the primary transfer area (area facing the primary transfer portion 27). (S29). The engine control CPU 51a repeats the process of step S29 until it determines that the toner patch formed on the surface of the photoreceptor 22 has reached the primary transfer area.

When it is determined in step S29 that the toner patch formed on the surface of the photoreceptor 22 has reached the primary transfer area (YES in S29), the engine control CPU 51a turns off the voltage applied to the primary transfer section 27 (S31). , it is determined whether or not the toner patch formed on the surface of the photoreceptor 22 has passed through the primary transfer area (S33). The engine control CPU 51a repeats the process of step S33 until it determines that the toner patch formed on the surface of the photoreceptor 22 has left the primary transfer area.

If it is determined in step S33 that the toner patch formed on the surface of the photoreceptor 22 has passed through the primary transfer area (YES in S33), the engine control CPU 51a sets the voltage applied to the primary transfer section 27 to the output value during printing. Return (S35) and return.

According to the present embodiment, the electrostatic latent image is formed on the surface of the photoreceptor 22 with the amount of laser light determined based on the forming conditions for forming the toner image based on the printed image on the paper. The density of the toner patch formed on the surface of body 22 can be set appropriately. As a result, contamination of the secondary transfer portion 29 by the toner of the toner patch with excessive density is suppressed, and the need for frequent cleaning of the secondary transfer portion 29 is eliminated. As a result, it is possible to suppress the occurrence of back stains and FD streaks while suppressing a decrease in productivity. In addition, since processing for creating toner patch images is not required, it is possible to prevent a decrease in productivity. Additionally, the amount of toner used in the toner patch can be reduced.

[Second embodiment]

In the present embodiment, the fogging margin is determined as a toner patch forming condition. When forming the toner patch PT, development is performed with the determined fogging margin. As a result, the density of the toner patch PT is appropriately set while supplying the toner to the photoreceptor blade 26, and contamination of the secondary transfer portion 29 by the toner of the toner patch PT is suppressed.

If the potential of the photoreceptor 22 after charging and the potential of the developing section 24 are the same, the toner in the developing section 24 will unnecessarily adhere to the non-image forming area of the photoreceptor 22, resulting in deterioration of image quality. might invite. The toner adhering to the non-image forming area of the photoreceptor 22 is called fog toner. Therefore, generally, the charging bias (voltage applied to the charging section 23) is made sufficiently larger than the developing bias (voltage applied to the developing section 24) to suppress the occurrence of fogging toner. The fogging margin is a value corresponding to the difference between the charging bias and the developing bias, as shown by the following formula (2).

Fogging margin=charging bias−developing bias (2)

(Basic Operation of Image Forming Apparatus)

Next, a basic operation of the image forming apparatus 1 according to this embodiment will be described.

FIG. 12 shows voltages applied to each of charging section 23, developing section 24, primary transfer section 27, and secondary transfer section 29 when image forming apparatus 1 executes a print job in the second embodiment of the present invention. FIG. 4 is a diagram showing an example of time change of applied voltage;

Referring to FIG. 12, at the timing when the areas on the surface of photoreceptor 22 where the electrostatic latent images of print images IM1, IM2, and IM3 are formed pass through the irradiation area of the laser light, engine control unit 51 Under the control of MFP controller 52, exposure unit 21 emits laser light to form electrostatic latent images of print images IM1, IM2, and IM3.

When a print job is started, engine control unit 51 applies a voltage corresponding to an output value during printing to each of charging unit 23 and developing unit 24 under the control of MFP controller 52 (charging unit 23, The printing output values of the developing section 24, the primary transfer section 27, and the secondary transfer section 29 are mutually different values). As a result, toner images of the print images IM1, IM2, and IM3 are formed on the surface of the photoreceptor 22 . The toner images of the print images IM1, IM2, and IM3 are transferred onto the intermediate transfer member 28 and sequentially transferred onto a sheet of paper passing between the intermediate transfer member 28 and the secondary transfer portion 29 .

On the other hand, at the timing when the area forming each of the toner patches PT on the surface of the photoreceptor 22 passes through the charging area of the charging section 23, the engine control section 51 applies a voltage to the charging section 23 without control from the MFP controller 52. The voltage to be applied is controlled to the output value at the time of patch formation. The patch-forming output value of the charging unit 23 is a value corresponding to the charging bias calculated using equation (2) from the value of the fogging margin determined by the method described later as the toner patch forming condition. As a result, generation of fogging toner during development of the toner patch PT is suppressed, and a situation in which an excessive amount of toner adheres to the surface of the photoreceptor 22 is suppressed.

At the timing when the toner image of the toner patch PT formed on the surface of the photoreceptor 22 passes through the area facing the primary transfer portion 27 , the engine control portion 51 transfers the image to the primary transfer portion 27 without control from the MFP controller 52 . The applied voltage is controlled so that the toner patch PT is not transferred to the intermediate transfer member 28 . As a result, most of the toner in the toner patch PT formed on the surface of the photoreceptor 22 is supplied to the photoreceptor blade 26 and is less likely to adhere to the intermediate transfer body 28 .

At the timing when the toner image of the toner patch PT formed on the surface of the intermediate transfer member 28 passes through the area facing the secondary transfer portion 29, the engine control portion 51 performs the secondary transfer without control from the MFP controller 52. The voltage applied to the portion 29 is controlled so that the toner patch PT is not transferred to the secondary transfer portion 29 . As a result, the toner in the toner patch PT formed on the surface of the intermediate transfer body 28 stays on the intermediate transfer body 28 and is less likely to adhere to the secondary transfer portion 29 .

Further, instead of controlling the voltage applied to the charging section 23 when forming the toner patch PT as shown in FIG. 12, the voltage applied to the developing section 24 may be controlled as shown in FIG. 13 below.

FIG. 13 shows voltages applied to each of charging section 23, developing section 24, primary transfer section 27, and secondary transfer section 29 when image forming apparatus 1 executes a print job in the second embodiment of the present invention. FIG. 10 is a diagram showing another example of time change of applied voltage;

Referring to FIG. 13, at the timing when the area forming each of the toner patches PT on the surface of photoreceptor 22 passes the developing area of developing unit 24, engine control unit 51, without control from MFP controller 52, The voltage applied to the developing unit 24 is controlled to the output value during patch formation. The patch formation output value of the developing unit 24 is a value corresponding to the developing bias calculated using equation (2) from the value of the fogging margin determined by the method described later as the toner patch supply condition. As a result, generation of fogging toner during development of the toner patch PT is suppressed, and a situation in which an excessive amount of toner adheres to the surface of the photoreceptor 22 is suppressed.

(Method of Determining Fog Margin)

Next, a method of determining the fogging margin in this embodiment will be described.

The engine control unit 51 determines the environmental value based on the absolute humidity value acquired from the environmental sensor 53 using the environmental value table when determining the toner patch forming conditions. Next, the engine control unit 51 determines a reference fogging margin using the reference fogging margin table. The reference fogging margin is determined using the resolution of the printed image, the peripheral speed of the photoreceptor, the color of the toner image formed on the photoreceptor, the cumulative number of rotations of the photoreceptor 22 obtained from the life management unit 54, and an environment table. is determined based on the environmental value determined by

14 and 15 are diagrams schematically showing reference fogging margin tables stored in the ROM 51b in the second embodiment of the present invention.

14 and 15, the reference fogging margin table includes the resolution of the printed image, the peripheral speed of the photoreceptor 22, the color of the toner image formed on the photoreceptor 22, and the photoreceptor obtained from the life management unit 54. 22 is a table describing the relationship between the cumulative number of rotations of No. 22 and the environment value determined using the environment table and the fogging margin. The reference fogging margin table defines a reference fogging margin for supplying the photoreceptor blade 26 with an amount of toner that does not cause FD streaks or back stains.

Specifically, FIGS. 14 and 15 show four reference fogging margin tables. When the resolution of the print image is 600 dpi, the reference fogging margin table in FIG. 14 is referenced, and when the resolution of the printing image is 1200 dpi, the reference fogging margin table in FIG. 15 is referenced. When the peripheral speed (rotational speed) of the photoreceptor is 200 mm/s, the reference fogging margin table described as "peripheral speed of photoreceptor: 200 mm/s" in FIG. is referred to, and when the peripheral speed of the photoreceptor is 100 mm/s, the reference fogging margin table described as "peripheral speed of photoreceptor: 100 mm/s" in FIG. 14(b) or FIG. 15(b) is referenced.

In one reference fogging margin table, the color of the toner image formed on the photoreceptor and the cumulative number of rotations of the photoreceptor are divided in the vertical direction. The color of the toner image formed on the photoreceptor is classified into four categories of KYMC, and the cumulative number of revolutions of the photoreceptor is classified into three categories of less than 300 krot, 300 krot to less than 600 krot, and 600 krot or more. In one reference fogging margin table, environmental values are divided into values 1 to 3 in the horizontal direction.

As an example, the resolution of the printed image is 600 dpi, the peripheral speed of the photoreceptor is 200 mm/s, the color of the toner image formed on the photoreceptor is M, and the cumulative rotation speed of the photoreceptor is 300 krot or more and less than 600 krot. and the environment value is "2", the reference fogging margin is determined to be "40" (V).

Engine control unit 51 may apply a charging bias and a developing bias calculated based on the determined reference fogging margin to each of charging unit 23 and developing unit 24 when forming toner patches. Further, the engine control section 51 may correct the determined reference fogging margin based on at least one of the developing bias and the amount of laser light when forming the toner image based on the printed image. In this case, the charging bias and the developing bias calculated based on the corrected fogging margin are applied to the charging section 23 and the developing section 24, respectively, when forming the toner patch.

Next, a method of correcting the reference fogging margin in this embodiment will be described.

FIG. 16 is a diagram schematically showing a fogging margin correction coefficient table corresponding to the developing bias stored in the ROM 51b in the second embodiment of the invention.

Referring to FIG. 16, the fogging margin correction coefficient table corresponding to the developing bias describes the relationship between the developing bias and the fogging margin correction coefficient when forming a toner image based on a print image. This fogging margin correction coefficient table is for correcting the fogging margin determined using the reference fogging margin table according to the development characteristics. In this fogging margin correction coefficient table, the colors of the toner image formed on the photoreceptor are divided into four KYMC in the vertical direction. In this fogging margin correction coefficient table, the developing bias is divided into three groups of −250V or more, −500V or more and less than −250V, and less than −500V in the horizontal direction.

As an example, when the color of the toner image formed on the photoreceptor is K and the developing bias when forming the toner image based on the printed image is less than -500 V, the fogging margin correction coefficient is "1.05 ” is determined.

The engine control unit 51 corrects (calculates) the fogging margin when forming the toner patch using the following equation (3).

Fogging margin (V) when forming a toner patch=reference fogging margin (V)×fogging margin correction coefficient (3)

FIG. 17 is a diagram schematically showing a fog margin correction coefficient table corresponding to the amount of laser light stored in the ROM 51b in the second embodiment of the invention.

Referring to FIG. 17, the fog margin correction coefficient table corresponding to the laser light amount is a table describing the relationship between the laser light amount and the fog margin correction coefficient when forming a toner image based on a print image. This fogging margin correction coefficient table is for correcting the reference fogging margin determined using the reference fogging margin table in accordance with the exposure characteristics. In this fogging margin correction coefficient table, the colors of the toner image formed on the photoreceptor are divided into four KYMC in the vertical direction. Further, in this fogging margin correction coefficient table, in the horizontal direction, the laser light amount is less than 1.0 mJ/m ² , 1.0 mJ/m ² or more and less than 3.0 mJ/m ² , and 3.0 mJ/m ² or more. It is divided into three.

As an example, when the color of the toner image formed on the photoreceptor is K and the amount of laser light when forming the toner image based on the printed image is less than 1.0 mJ/m ² , the fogging margin correction coefficient is It is determined to be "0.9".

The engine control unit 51 uses Equation (3) to correct (calculate) the fogging margin when forming the toner patch.

By adopting the fogging margin determined by the above-described method when forming the toner patch, the fogging margin is appropriately set based on the print image forming conditions while supplying the toner to the photoreceptor blade 26, and the toner patch is formed. Contamination of the secondary transfer portion 29 by the fogging toner is suppressed.

FIG. 18 is a subroutine of toner patch processing (S5) of FIG. 10 according to the second embodiment of the present invention, which is a subroutine of toner patch processing when charging bias is controlled during toner patch formation.

Referring to FIG. 18, in the toner patch process, the engine control CPU 51a determines the fogging margin when forming the toner patch (S41), and switches the charging bias to a value calculated based on the determined fogging margin ( S43). Next, the engine control CPU 51a determines whether or not a toner patch having a target length has been formed on the surface of the photoreceptor 22 (S45). The engine control CPU 51a repeats the process of step S45 until it determines that the toner patch of the target length has been formed on the surface of the photoreceptor 22. FIG.

If it is determined in step S45 that the toner patch of the target length has been formed on the surface of the photoreceptor 22 (YES in S45), the engine control CPU 51a restores the charging bias to the original value (S47). After that, the engine control CPU 51a performs steps S49 to S55, which are the same as steps S29 to S35 in FIG. 11, and returns.

FIG. 19 is a subroutine of the toner patch processing (S5) of FIG. 10 according to the second embodiment of the present invention, and is a subroutine of the toner patch processing when controlling the developing bias when forming the toner patch.

Referring to FIG. 19, in the toner patch process, the engine control CPU 51a determines a fogging margin when forming a toner patch (S61), and switches the developing bias to a value calculated based on the determined fogging margin ( S63). Next, the engine control CPU 51a determines whether or not a toner patch having a target length has been formed on the surface of the photoreceptor 22 (S65). The engine control CPU 51a repeats the process of step S65 until it determines that the toner patch of the target length has been formed on the surface of the photoreceptor 22. FIG.

If it is determined in step S65 that the toner patch of the target length has been formed on the surface of the photoreceptor 22 (YES in S65), the engine control CPU 51a returns the developing bias to the original value (S67). After that, the engine control CPU 51a performs steps S69 to S75, which are the same as steps S29 to S35 in FIG. 11, and returns.

The configuration and operation of image forming apparatus 1 according to the present embodiment other than those described above are the same as those of the image forming apparatus according to the first embodiment, and therefore description thereof will not be repeated.

According to the present embodiment, it is possible to appropriately set the fogging margin for forming the toner patch based on the forming conditions for forming the toner image based on the print image on the paper. As a result, contamination of the secondary transfer portion 29 due to fogging toner when forming toner patches is suppressed, and the need for frequent cleaning of the secondary transfer portion 29 is eliminated. As a result, it is possible to suppress the occurrence of back stains and FD streaks while suppressing a decrease in productivity. In addition, since processing for creating toner patch images is not required, it is possible to prevent a decrease in productivity. Additionally, the amount of toner used in the toner patch can be reduced.

[Third Embodiment]

In this embodiment, the IDC sensor 56 detects the density of the toner patch transferred to the intermediate transfer member 28, and based on the detected density, the conditions for forming the toner patch after detection by the IDC sensor 56 are corrected. .

FIG. 20 is a diagram showing the relationship between the amount of toner patches on the surface of the intermediate transfer member 28 and the back side stain threshold TH1 and the FD streak threshold TH2 in the third embodiment of the invention.

Referring to FIG. 20, the back side staining threshold TH1 is a threshold regarding the presence or absence of back side staining (a phenomenon in which the paper is stained with toner adhering to the secondary transfer portion 29). That is, when the amount of toner patches on the surface of the intermediate transfer member 28 is greater than the back staining threshold TH1, the back staining occurs on the paper. The backside contamination threshold TH1 is constant regardless of the primary transfer efficiency, which is the transfer efficiency of the toner image from the photosensitive member 22 to the intermediate transfer member 28 by the primary transfer portion 27 .

The FD streak threshold TH2 (<TH1) is a threshold regarding the presence or absence of FD streaks (residual toner streaks along the circumferential direction of the surface of the photoreceptor). That is, when the amount of toner patches on the surface of the intermediate transfer member 28 is less than the FD streak threshold TH2, FD streaks are generated on the surface of the photoreceptor 22 . The FD muscle threshold TH2 increases in proportion to the primary transfer efficiency. As the primary transfer efficiency increases, the amount of toner patches adhering to the intermediate transfer member 28 increases, and the amount of toner patches supplied to the photoreceptor blade 26 decreases, resulting in a situation in which FD streaks are likely to occur. is.

Therefore, when the amount of toner patches on the surface of the intermediate transfer member 28 calculated based on the density detected by the IDC sensor 56 is higher than the back side dirt threshold TH1, the engine control unit 51 controls the toner patch after the detection by the IDC sensor 56. First, the amount of toner patch formed on the surface of photoreceptor 22 is reduced. Further, when the amount of toner patches on the surface of the intermediate transfer member 28 calculated based on the density detected by the IDC sensor 56 is lower than the FD streak threshold TH2, the engine control unit 51 controls the exposure after detection by the IDC sensor 56. The amount of toner patch that forms on the surface of body 22 is increased.

The amount of the toner patch depends on the length L2 (FIG. 3) of the toner patch and the density of the toner patch, as shown in equation (4) below. Therefore, the amount of the toner patch can be controlled by at least one of the length L2 of the toner patch and the density of the toner patch.

Toner patch amount (g)=Toner patch length L2 (m ² )×Toner patch density (g/m ² ) (4)

The length L2 of the toner patch can be changed according to the exposure time when forming the toner patch. The density of the toner patch can be changed by adjusting the amount of laser light and the fogging margin when forming the toner patch.

The FD muscle threshold TH2 is determined using the primary transfer efficiency table shown in FIG. 21 and the FD muscle threshold table shown in FIG. The FD muscle threshold TH2 is changed according to the primary transfer efficiency.

FIG. 21 is a diagram schematically showing a primary transfer efficiency table stored in the ROM 51b in the third embodiment of the invention.

Referring to FIG. 21, the primary transfer efficiency table is the color of the toner image formed on photoreceptor 22, the cumulative number of rotations of photoreceptor 22 obtained from life management unit 54, and the environment determined using the environment table. 4 is a table describing the relationship between values and primary transfer efficiency. The primary transfer efficiency tends to be low in a low-temperature, low-humidity environment, high in a high-temperature, high-humidity environment, and tends to decrease as the degree of wear of the photoreceptor progresses.

In the primary transfer efficiency table, the color of the toner image formed on the photoreceptor and the cumulative number of rotations of the photoreceptor are divided in the vertical direction. The color of the toner image formed on the photoreceptor is classified into four categories of KYMC, and the cumulative number of revolutions of the photoreceptor is classified into three categories of less than 300 krot, 300 krot to less than 600 krot, and 600 krot or more. In one reference light intensity table, environmental values are divided into values 1 to 3 in the horizontal direction.

As an example, when the color of the toner image formed on the photoreceptor is K, the cumulative number of rotations of the photoreceptor is 300 krot or more and less than 600 krot, and the environmental value is "2", the primary transfer efficiency is "90 ” (%).

Note that if the image forming apparatus 1 includes the IDC sensor 55 that detects the density of the toner image remaining on the surface of the photosensitive member 22 without being transferred, instead of using the primary transfer efficiency table, the following equation (5 ) may be used to calculate the primary transfer efficiency.

Primary transfer efficiency (%)=(density of toner image formed on surface of intermediate transfer member 28)/{(density of toner image remaining on surface of photoreceptor 22)+(density of toner image formed on surface of intermediate transfer member 28) density of toner image)}×100 (5)

FIG. 22 is a diagram schematically showing the FD muscle threshold table stored in the ROM 51b in the third embodiment of the invention.

Referring to FIG. 22, the FD streak threshold table is a table describing the relationship between the primary transfer efficiency and the amount of toner serving as the FD streak threshold. In this FD streak threshold table, the colors of the toner image formed on the photoreceptor are divided into four KYMC in the vertical direction. Further, in this FD streak threshold table, the primary transfer efficiency is divided into three categories in the horizontal direction: less than 88%, 88% or more and less than 93%, and 93% or more.

As an example, when the color of the toner image formed on the photosensitive member is K and the primary transfer efficiency is 93% or higher, the FD streak threshold is determined to be "1.7 (g)".

FIG. 23 is a subroutine of the toner patch density detection process (S7) of FIG. 10 according to the third embodiment of the invention.

Referring to FIG. 23, in the toner patch density detection process, the engine control CPU 51a determines whether or not the toner patch has reached the detection position of the IDS sensor 56 (S81). The engine control CPU 51a repeats the process of step S81 until it determines that the toner patch has reached the detection position of the IDS sensor 56. FIG.

If it is determined in step S81 that the toner patch has reached the detection position of the IDS sensor 56 (YES in S81), the engine control CPU 51a detects the density of the toner patch on the surface of the intermediate transfer body 28 (S83), It is determined whether or not the amount of toner patches on the surface of the transfer body 28 is equal to or greater than the backside contamination threshold (S85).

In step S85, when it is determined that the amount of toner patches on the surface of the intermediate transfer member 28 is equal to or greater than the backside stain threshold value (YES in S85), the engine control CPU 51a controls the toner patches to be formed on the surface of the photoreceptor 22 thereafter. is decreased (S87), and the process is terminated.

In step S85, if it is determined that the amount of toner patches on the surface of the intermediate transfer body 28 is less than the backside dirt threshold (NO in S85), the engine control CPU 51a determines that the amount of toner patches on the surface of the intermediate transfer body 28 is FD. It is determined whether or not it is equal to or less than the muscle threshold (S89).

In step S89, if it is determined that the amount of toner patches on the surface of the intermediate transfer body 28 is equal to or less than the FD streak threshold (YES in S89), the engine control CPU 51a controls the toner patches to be formed on the surface of the photoreceptor 22 thereafter. is increased (S91), and the process ends.

If it is determined in step S89 that the toner patch amount on the surface of the intermediate transfer member 28 is greater than the FD streak threshold (NO in S89), the engine control CPU 51a returns.

The configuration and operation of image forming apparatus 1 according to the present embodiment other than those described above are the same as those of the image forming apparatus according to the first embodiment, and therefore description thereof will not be repeated.

The back contamination occurs when a large amount of toner adheres to the intermediate transfer member 28 and the large amount of toner locally adheres to a part of the surface of the secondary transfer portion 29 . According to this embodiment, the amount of toner adhering to the intermediate transfer member 28 as a result of forming the toner patch on the surface of the photosensitive member 22 is actually detected, and the detection result is fed back to the density of the next toner patch. Therefore, it is possible to prevent a large amount of toner from adhering to the surface of the intermediate transfer member 28, and it is possible to further effectively prevent the back side staining.

(Modification of the third embodiment)

Next, a modified example of this embodiment will be described.

In the first and second modifications of the present embodiment, when the toner patches are formed, each of the plurality of toner patches is formed on each of the plurality of photoreceptors 22 (here, four colors of YMCK), and a plurality of toner patches are formed. Assume a situation where each of the patches are transferred to the intermediate transfer member 28 on top of each other.

FIG. 24 shows the relationship between the number of colors of toner patches superimposed and transferred on the surface of the intermediate transfer body 28 and the amount of toner patches on the surface of the intermediate transfer body 28 in the third embodiment of the present invention. FIG. 4 is a diagram showing;

Referring to FIG. 24, the number of colors of toner patches to be superimposed and transferred on the surface of intermediate transfer member 28 (hereinafter sometimes referred to as the number of superimposed colors) is 4, 3, 2, and 1 color. , the amount of toner patch on the surface of intermediate transfer member 28 at a given location decreases. As a result, for example, as a result of setting the number of overlapping colors to four, if the amount of toner patches on the surface of the intermediate transfer member 28 exceeds the back stain threshold value TH1, the subsequent number of overlapping colors is reduced, and the intermediate transfer The amount of toner patch on the surface of body 28 can be reduced below the back smear threshold TH1.

Therefore, as a first modification of the present embodiment, the engine control unit 51 corrects the number of overlapping colors after detection by the IDC sensor 56 based on the density detected by the IDC sensor 56 .

Specifically, when the amount of toner patches indicated by the density detected by the IDC sensor 56 is higher than the backside stain threshold TH1, the engine control unit 51 reduces the number of overlapping colors after detection by the IDC sensor.

When decreasing the number of superimposed colors, the priority information stored in the ROM 51b (for example, the priority order information of Y, M, K, and C from the highest priority to the lowest priority). Based on this, when forming toner patches on the surface of the photoreceptor 22 corresponding to colors with high priority among the plurality of photoreceptors 22 (here, Y, M, and K), the priority among the plurality of photoreceptors 22 is determined. A toner patch may not be formed on the surface of the photoreceptor 22 corresponding to a color of low intensity (here, C). Priority may be determined based on the likelihood of FD muscle development.

FIG. 25 is a subroutine of the toner patch density detection process (S7) of FIG. 10 in the first modification of the third embodiment of the invention.

Referring to FIG. 25, in the toner patch density detection process, the engine control CPU 51a determines whether or not the toner patch has reached the detection position of the IDS sensor 56 (S101). The engine control CPU 51a repeats the process of step S101 until it determines that the toner patch has reached the detection position of the IDS sensor 56. FIG.

If it is determined in step S101 that the toner patch has reached the detection position of the IDS sensor 56 (YES in S101), the engine control CPU 51a detects the density of the toner patch on the surface of the intermediate transfer body 28 (S103), It is determined whether or not the amount of toner patches on the surface of the transfer body 28 is equal to or greater than the backside contamination threshold (S105).

In step S105, if it is determined that the amount of toner patches on the surface of the intermediate transfer member 28 is equal to or greater than the backside contamination threshold (YES in S105), the engine control CPU 51a reduces the number of overlapping colors thereafter (S107), and returns. do.

In step S105, when it is determined that the amount of toner patches on the surface of the intermediate transfer member 28 is less than the backside stain threshold value (NO in S105), the engine control CPU 51a returns.

According to the first modification, by reducing the number of superimposed colors, it is possible to prevent a large amount of toner from locally adhering to the surface of the intermediate transfer member 28, thereby further effectively preventing the occurrence of back stains. can be deterred.

FIG. 26 is a diagram schematically showing a toner image formed on the surface of the intermediate transfer member 28 in the second modified example of the third embodiment of the invention.

Referring to FIG. 26, as a second modified example of the present embodiment, engine control unit 51 determines the density detected by IDC sensor 56, and the image transferred to intermediate transfer member 28 after detection by IDC sensor 56. correcting the position of at least one of the plurality of toner patches formed between the toner images of the plurality of print images.

Specifically, when the amount of toner patches indicated by the density detected by the IDC sensor 56 is higher than the backside stain threshold TH1, the engine control unit 51 selects at least one of the plurality of toner patches to be transferred onto the intermediate transfer member . The position of one toner patch and the position of at least one of the plurality of toner patches formed between the toner images of each of the plurality of print images IM1, IM2, and IM3 is defined as a plurality of toner patches. of the other toner patches.

Here, the positions of the C and K toner patches among the YMCK toner patches that have been superimposed and transferred to the intermediate transfer member 28 are shifted. As a result, after the detection by the IDC sensor 56, on the surface of the intermediate transfer member 28, between the toner images of the print images IM1, IM2, and IM3, the toner patch PT1 in which Y and M are superimposed and transferred, A toner patch PT2 in which C and K are superimposed and transferred is formed side by side. As a result, the number of overlapping colors of each of toner patches PT1 and PT2 is reduced.

Note that the toner patch PT2 may be shifted to the downstream side in the rotational direction of the intermediate transfer member 28 relative to the toner patch PT1, or may be shifted to the downstream side. Also, the toner patch PT2 may be separated from the toner patch PT1, or may be adjacent to the toner patch PT1.

By the way, in order to form toner patches of all the colors to be formed by the method of shifting the positions of the toner patches as shown in FIG. must be long enough. Therefore, engine control unit 51 may change the toner patch forming method depending on whether or not the distance L3 between the toner images of print images IM1, IM2, and IM3 satisfies the following equation (6).

Interval L3≦value S×toner patch length L2+moving distance of intermediate transfer member corresponding to time required for switching output values between print image formation and toner patch formation (6)

The value S in the formula (6) is an integer obtained by rounding up the value below the decimal point in the calculation result of "the number of toner patch colors to be formed within one interval L3/the maximum number of superimposed colors that do not cause back staining". be. The number of colors of toner patches to be formed within one interval L3 is normally "4" (the total number of photoreceptors 22 in the image forming apparatus 1). It may be the number of colors determined using the patch formation timing table (FIG. 29).

When the interval L3 satisfies the expression (6), the interval L3 is sufficiently long, and the image forming apparatus 1 can form toner patches of all colors within one interval L3 without causing back stains. is in a state where it can be formed into In this case, the engine control unit 51 forms toner patches of all colors to be formed within one interval L3 by shifting the positions of the toner patches as shown in FIG.

On the other hand, when the interval L3 does not satisfy the expression (6), the interval L3 is short, and the image forming apparatus 1 allows the toner patches of all the colors to be formed to be formed within the interval L3 without causing backside staining. It is in a state of being unable to form within. In this case, the engine control unit 51 forms only the toner patches with the maximum number of superimposed colors that do not cause back staining within one interval L3. In this case, based on the priority information stored in the ROM 51b, a toner patch of each color is formed inside each of the plurality of intervals L3 in order from the color having the highest priority among the plurality of photoreceptors 22. may

FIG. 27 is a subroutine of the toner patch density detection process (S7) of FIG. 10 in the second modification of the third embodiment of the invention.

Referring to FIG. 27, in the toner patch density detection process, the engine control CPU 51a determines whether or not the toner patch has reached the detection position of the IDS sensor 56 (S111). The engine control CPU 51a repeats the process of step S111 until it determines that the toner patch has reached the detection position of the IDS sensor 56. FIG.

If it is determined in step S111 that the toner patch has reached the detection position of the IDS sensor 56 (YES in S111), the engine control CPU 51a detects the density of the toner patch on the surface of the intermediate transfer body 28 (S113), It is determined whether or not the amount of toner patches on the surface of the transfer body 28 is equal to or greater than the backside contamination threshold (S115).

In step S115, when it is determined that the amount of toner patches on the surface of the intermediate transfer member 28 is less than the backside stain threshold value (NO in S115), the engine control CPU 51a returns.

In step S115, when it is determined that the amount of toner patches on the surface of the intermediate transfer member 28 is equal to or greater than the backside stain threshold (YES in S115), the engine control CPU 51a determines that the interval L3 between the printed images satisfies equation (6). (S117).

In step S117, when it is determined that the interval L3 between the printed images satisfies the expression (6) (YES in S117), the engine control CPU 51a shifts the positions of the toner patches to generate toner of all colors to be formed. A patch is formed within one interval L3 (S119), and the process returns.

In step S117, when it is determined that the interval L3 between the printed images does not satisfy the expression (6) (NO in S117), the engine control CPU 51a arranges the toner patches of each color in descending order of priority by a plurality of intervals. Form inside each L3 (S121) and return.

According to the second modification, by dispersing the toner patches on the surface of the intermediate transfer body 28 as necessary, it is possible to prevent a large amount of toner from locally adhering to the surface of the intermediate transfer body 28. Therefore, it is possible to more effectively suppress the occurrence of back stains.

[others]

(1) The engine control unit 51 determines the amount of toner based on at least one of the degree of wear of the photoreceptor 22, the environment of the image forming apparatus 1, and the total number of toner patches formed since the start of the image forming apparatus 1. It may be determined whether or not to form a patch. Then, when it is determined that a toner patch needs to be formed, the necessary positions (positions on the surface of the photoreceptor 22 between the toner images of each of the plurality of print images of the print job and the position of the last print image in the print job) are determined. At least one of the positions behind the toner image may form a toner patch. As an example, the engine control unit 51 may use a patch formation necessity table shown in FIG. 28 to determine the necessity of toner patch formation.

FIG. 28 is a diagram schematically showing a patch formation necessity table stored in the ROM 51b in another embodiment of the present invention.

Referring to FIG. 28, the patch formation necessity table describes the relationship between the color of the toner image formed on photoreceptor 22 and the environment value determined using the environment table and the necessity of toner patch formation. It is a table.

In the patch formation necessity table, the colors of the toner image formed on the photoreceptor are divided into four KYMC in the vertical direction. In the patch formation necessity table, environmental values are divided into values 1 to 3 in the horizontal direction.

As an example, if the color of the toner image formed on the photoreceptor is K and the environmental value is "2", it is determined that the formation of the toner patch is unnecessary.

(2) The engine control unit 51 decides whether to form toner patches based on at least one of the degree of wear of the photoreceptor 22, the environment of the image forming apparatus 1, and the number of toner patches formed from the start of the print job. You can decide the timing. As an example, the engine control unit 51 may use the patch formation timing table shown in FIG. 28 to determine the timing for forming the toner patches.

FIG. 29 is a diagram schematically showing a patch formation timing table stored in the ROM 51b in another embodiment of the invention.

Referring to FIG. 29, the patch formation timing table includes the number of toner patches formed from the start of the print job, the color of the toner image formed on photoreceptor 22, the environment value determined using the environment table, It is a table describing the relationship with the distance L1.

The distance L1 is a value that indicates the timing of toner patch formation. When forming the first toner patch from the start of the print job, the distance L1 is the distance from the rotation start position of the photoreceptor 22 at the start of the print job to the toner patch formation start position (distance L1a in FIG. 3). ). When forming the second and subsequent toner patches from the start of the print job, the distance L1 is the distance from the formation end position of the previous toner patch to the formation start position of the next toner patch (distance L1b in FIG. 3). corresponds to

FIG. 29 shows two patch formation timing tables. When forming the first toner patch from the start of the print job, the patch formation timing table of FIG. 29A is referred to. , the patch formation timing table of FIG. 29(b) is referred to.

In one patch formation necessity table, the colors of the toner image formed on the photoreceptor are divided into four KYMC in the vertical direction. In the patch formation necessity table, environmental values are divided into values 1 to 3 in the horizontal direction.

As an example, when forming the first toner patch from the start of the print job, if the color of the toner image formed on the photoreceptor is K and the environmental value is "1", the distance L1 is It is determined to be "400" (mm).

(3) The engine control unit 51 may determine the toner patch length L3 based on at least one of the degree of wear of the photoreceptor 22 and the environment of the image forming apparatus 1 . As an example, the engine control unit 51 may determine the toner patch length L3 using the patch length table shown in FIG.

FIG. 30 is a diagram schematically showing a patch length table stored in the ROM 51b in another embodiment of the invention.

Referring to FIG. 30, the patch length table is a table describing the relationship between the color of the toner image formed on photoreceptor 22, the environment value determined using the environment table, and the toner patch length L3. is.

In the patch length table, the colors of the toner image formed on the photoreceptor are divided into four KYMC in the vertical direction. In the patch formation necessity table, environmental values are divided into values 1 to 3 in the horizontal direction.

As an example, when the color of the toner image formed on the photosensitive member is K and the environmental value is "1", the toner patch length L3 is determined to be "20" (mm).

(4) The image forming apparatus may directly transfer the toner image formed on the surface of the photoreceptor onto a sheet without using an intermediate transfer belt (direct transfer method).

The embodiments and modifications described above can be combined as appropriate.

The processing in the above-described embodiments and modifications may be performed by software or by using hardware circuits. Also, it is possible to provide a program for executing the processes in the above-described embodiments and modifications, and record the program on a recording medium such as a CD-ROM, a flexible disk, a hard disk, a ROM, a RAM, or a memory card. It may be provided to the user. A program is executed by a computer such as a CPU. Alternatively, the program may be downloaded to the device via a communication line such as the Internet.

The above-described embodiments and modifications should be considered illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the meaning and range of equivalents of the scope of the claims.

1 Image forming apparatus (an example of an image forming apparatus)
1a Image forming apparatus main body 10 Paper transport unit 11 Paper feed tray 12 Paper feed roller 13 Registration roller 14 Paper discharge roller 15 Paper discharge tray 20 Toner image forming unit 20A Image forming unit 21 Exposure unit (an example of laser beam irradiation means)
22 Photoreceptor (an example of a photoreceptor)
23 charging unit (an example of charging unit)
24 development unit (an example of development unit)
25 Eraser section 26 Photoreceptor blade (an example of removing means)
27 Primary transfer unit (an example of a transfer unit)
28 Intermediate transfer body (an example of intermediate transfer body)
28a rotating roller 29 secondary transfer section (an example of a secondary transfer section)
30 fixing device 51 engine control unit 51a engine control CPU (Central Processing Unit) (toner patch formation control means, transfer voltage control means, condition correction means, color number correction means, position correction means, execution determination means, timing determination means, and an example of length determination means)
51b ROM (Random Access Memory) (an example of a storage device)
51c RAM
52 MFP (Multi Function Peripheral) controller (an example of print control means)
53 Environmental sensor 54 Lifespan management unit 55, 56 IDC (Image Density Control) sensor (an example of density detection means)
57 High pressure section IM1, IM2, IM3 Print image PT, PT1, PT2 Toner patch TR Transport path

Claims (27)

a photoreceptor;
a transcription unit;
An image forming apparatus comprising a removing unit for removing toner on the surface of the photoreceptor,
print control means for performing control to form a toner image based on a print image on paper under a first formation condition using at least the photoreceptor and the transfer unit;
toner patch formation control means for forming toner patches on the surface of the photoreceptor under second formation conditions determined based on the first formation conditions when the toner image is formed on the paper by the print control means; ,
When the toner patch formed on the surface of the photoreceptor passes through a portion facing the transfer unit, the voltage applied to the transfer unit is controlled to a voltage at which the toner patch formed on the photoreceptor is not transferred. a transfer voltage control means for
an intermediate transfer member onto which the toner image formed on the photoconductor by the transfer unit is transferred;
density detection means for detecting the density of the toner patch transferred onto the intermediate transfer member;
condition correction means for correcting the second forming condition after detection by the density detection means based on the density detected by the density detection means;
When the amount of toner patches indicated by the density detected by the density detection means is higher than a first threshold value, the condition correction means determines whether the toner patches to be formed on the surface of the photoreceptor after detection by the density detection means reduce the amount of
If the density detected by the density detecting means is lower than the amount of toner patches indicated by a second threshold value lower than the first threshold value, the condition correcting means controls the amount of toner patches after detection by the density detecting means. increasing the amount of toner patches transferred to the surface of the photoreceptor to
The image forming apparatus, wherein the second threshold is changed according to primary transfer efficiency, which is transfer efficiency of the transfer unit. a photoreceptor;
a transcription unit;
An image forming apparatus comprising a removing unit for removing toner on the surface of the photoreceptor,
print control means for performing control to form a toner image based on a print image on paper under a first formation condition using at least the photoreceptor and the transfer unit;
toner patch formation control means for forming toner patches on the surface of the photoreceptor under second formation conditions determined based on the first formation conditions when the toner image is formed on the paper by the print control means; ,
When the toner patch formed on the surface of the photoreceptor passes through a portion facing the transfer unit, the voltage applied to the transfer unit is controlled to a voltage at which the toner patch formed on the photoreceptor is not transferred. a transfer voltage control means for
an intermediate transfer member onto which the toner image formed on the photoconductor by the transfer unit is transferred;
density detection means for detecting the density of the toner patch transferred onto the intermediate transfer member;
a plurality of said photoreceptors, and each of said plurality of photoreceptors corresponds to each of a plurality of colors;
each of the plurality of toner patches formed on each of the plurality of photoreceptors by the toner patch formation control means is superimposed and transferred onto the intermediate transfer member;
color number correcting means for correcting, based on the density detected by the density detecting means, the number of colors of the plurality of toner patches to be superimposed and transferred onto the intermediate transfer body after detection by the density detecting means; image forming apparatus. When the amount of toner patches indicated by the density detected by the density detection means is higher than a first threshold value, the color number correction means causes the toner patches to be superimposed and transferred onto the intermediate transfer body after detection by the density detection means. 3. The image forming apparatus of claim 2 , wherein the number of colors in the plurality of toner patches is reduced. When the amount of toner patches indicated by the density detected by the density detection means is higher than the first threshold value, the color number correction means selects the photoreceptors corresponding to colors with low priority among the plurality of photoreceptors. 4. The image forming apparatus according to claim 3 , wherein the toner patch is not formed on the surface of the body. a photoreceptor;
a transcription unit;
An image forming apparatus comprising a removing unit for removing toner on the surface of the photoreceptor,
print control means for performing control to form a toner image based on a print image on paper under a first formation condition using at least the photoreceptor and the transfer unit;
toner patch formation control means for forming toner patches on the surface of the photoreceptor under second formation conditions determined based on the first formation conditions when the toner image is formed on the paper by the print control means; ,
When the toner patch formed on the surface of the photoreceptor passes through a portion facing the transfer unit, the voltage applied to the transfer unit is controlled to a voltage at which the toner patch formed on the photoreceptor is not transferred. a transfer voltage control means for
an intermediate transfer member onto which the toner image formed on the photoconductor by the transfer unit is transferred;
density detection means for detecting the density of the toner patch transferred onto the intermediate transfer member;
a plurality of said photoreceptors, and each of said plurality of photoreceptors corresponds to each of a plurality of colors;
each of the plurality of toner patches formed on each of the plurality of photoreceptors by the toner patch formation control means is superimposed and transferred onto the intermediate transfer member;
a position of at least one of the plurality of toner patches to be transferred onto the intermediate transfer member after detection by the density detection means, based on the density detected by the density detection means; The image forming apparatus further comprising position correcting means for correcting the position of at least one of the plurality of toner patches formed between the toner images of the print image. When the amount of the toner patch indicated by the density detected by the density detection means is higher than a first threshold value, the position correction means selects at least one toner patch among the plurality of toner patches to be transferred onto the intermediate transfer body. position of at least one toner patch among the plurality of toner patches formed between toner images of the plurality of print images; 6. The image forming apparatus according to claim 5 , wherein the position is shifted from the position of . further comprising a secondary transfer unit for transferring a toner image based on the printed image from the intermediate transfer member to the paper;
The transfer voltage control means controls the voltage applied to the secondary transfer portion so that the toner patch formed on the intermediate transfer member is not transferred when the toner patch passes through the area facing the secondary transfer portion. 7. The image forming apparatus according to claim 1 , wherein the voltage is further controlled. The voltage at which the toner patch formed on the intermediate transfer member is not transferred is a voltage lower than the voltage at the time of forming the toner image of the print image, zero, or the same potential as the toner patch formed on the intermediate transfer member. 8. The image forming apparatus according to claim 7 , wherein the voltage is: 9. The image forming apparatus according to any one of claims 1 to 8 , wherein said first forming condition includes a developing bias when forming a toner image based on said print image. 10. The image forming apparatus according to any one of claims 1 to 9 , wherein said first forming condition includes a laser light amount when forming a toner image based on said print image. The first forming condition is at least one of the rotation speed of the photoreceptor, the color of the toner image formed on the photoreceptor, the degree of wear of the photoreceptor, the environment of the image forming apparatus, and the resolution of the printed image. The image forming apparatus according to any one of claims 1 to 10 , comprising any one parameter. 12. The image forming apparatus according to claim 11 , further comprising a storage device that stores a table indicating the relationship between said at least one parameter and said second forming condition. 13. The image forming apparatus according to claim 1 , wherein said first forming condition is a condition determined by image stabilization processing performed by said image forming apparatus. The first forming condition according to any one of claims 1 to 12 , wherein the first forming condition is a condition determined based on at least one of the environment of the image forming apparatus and the degree of consumption of consumables of the image forming apparatus. image forming device. further comprising laser beam irradiation means for irradiating a laser beam for forming an electrostatic latent image, which is a source of a toner image, on the surface of the photoreceptor;
15. The image forming apparatus according to any one of claims 1 to 14 , wherein said second forming condition is the amount of laser light irradiated by said laser light irradiation means. a charging unit to which a charging bias is applied to charge the surface of the photoreceptor;
a developing unit to which a developing bias is applied to develop the electrostatic latent image formed on the surface of the photoreceptor;
15. The image forming apparatus according to claim 1 , wherein said second forming condition is a difference between said charging bias and said developing bias. 17. The image forming apparatus according to claim 16 , wherein said toner patch formation control means applies said charging bias or said developing bias having a magnitude calculated based on said difference. The voltage at which the toner patch formed on the photoreceptor is not transferred is a voltage lower than the voltage at the time of forming the toner image of the print image, zero, or the same potential as the toner patch formed on the photoreceptor. The image forming apparatus according to any one of claims 1 to 17 , wherein the voltage is voltage. Necessity of forming the toner patch is determined based on at least one of the degree of wear of the photoreceptor, the environment of the image forming apparatus, and the total number of times the toner patch has been formed since the image forming apparatus was started. 19. The image forming apparatus according to any one of claims 1 to 18 , further comprising execution determining means for determining. Timing determining means for determining the timing of forming the toner patches based on at least one of the degree of wear of the photoreceptor, the environment of the image forming apparatus, and the number of toner patches formed from the start of the print job. The image forming apparatus according to any one of claims 1 to 19 , comprising: 21. The image forming apparatus according to any one of claims 1 to 20 , further comprising length determining means for determining the length of said toner patch based on at least one of the degree of wear of said photoreceptor and the environment of said image forming apparatus. The described image forming apparatus. An image forming apparatus comprising a photoreceptor, a transfer section, removing means for removing toner on the surface of the photoreceptor, and an intermediate transfer body onto which the toner image formed on the photoreceptor by the transfer section is transferred. A control method of
The control method is
a print control step of performing control to form a toner image based on a print image on paper under a first formation condition using at least the photoreceptor and the transfer unit;
a toner patch formation control step of forming a toner patch on the surface of the photoreceptor under a second formation condition determined based on the first formation condition when forming a toner image on a sheet in the print control step; ,
When the toner patch formed on the surface of the photoreceptor passes through a portion facing the transfer unit, the voltage applied to the transfer unit is controlled to a voltage at which the toner patch formed on the photoreceptor is not transferred. a transfer voltage control step for
a density detection step of detecting the density of the toner patch transferred onto the intermediate transfer member;
a condition correction step of correcting the second forming condition after detection by the density detection step based on the density detected by the density detection step;
If the amount of toner patches indicated by the density detected in the density detection step is higher than a first threshold value, in the condition correction step, toner patches formed on the surface of the photoreceptor after detection by the density detection step. reduce the amount of
If the toner patch amount indicated by the density detected in the density detection step is lower than a second threshold value lower than the first threshold value, then in the condition correction step, after detection by the density detection step, increasing the amount of toner patches transferred to the surface of the photoreceptor to
A control method for an image forming apparatus, wherein the second threshold value is changed according to primary transfer efficiency, which is transfer efficiency of the transfer unit. An image forming apparatus comprising a photoreceptor, a transfer section, removing means for removing toner on the surface of the photoreceptor, and an intermediate transfer body onto which the toner image formed on the photoreceptor by the transfer section is transferred. A control method of
The control method is
a print control step of performing control to form a toner image based on a print image on paper under a first formation condition using at least the photoreceptor and the transfer unit;
a toner patch formation control step of forming a toner patch on the surface of the photoreceptor under a second formation condition determined based on the first formation condition when forming a toner image on a sheet in the print control step; ,
When the toner patch formed on the surface of the photoreceptor passes through a portion facing the transfer unit, the voltage applied to the transfer unit is controlled to a voltage at which the toner patch formed on the photoreceptor is not transferred. a transfer voltage control step for
a density detection step of detecting the density of the toner patch transferred to the intermediate transfer member;
a plurality of said photoreceptors, and each of said plurality of photoreceptors corresponds to each of a plurality of colors;
each of the plurality of toner patches formed on each of the plurality of photoreceptors in the toner patch formation control step is superimposed and transferred onto the intermediate transfer member;
further comprising a color number correction step of correcting the number of colors of the plurality of toner patches to be superimposed and transferred onto the intermediate transfer member after detection by the density detection step, based on the density detected by the density detection step; A control method for an image forming apparatus. An image forming apparatus comprising a photoreceptor, a transfer section, removing means for removing toner on the surface of the photoreceptor, and an intermediate transfer body onto which the toner image formed on the photoreceptor by the transfer section is transferred. A control method of
The control method is
a print control step of performing control to form a toner image based on a print image on paper under a first formation condition using at least the photoreceptor and the transfer unit;
a toner patch formation control step of forming a toner patch on the surface of the photoreceptor under a second formation condition determined based on the first formation condition when forming a toner image on a sheet in the print control step; ,
When the toner patch formed on the surface of the photoreceptor passes through a portion facing the transfer unit, the voltage applied to the transfer unit is controlled to a voltage at which the toner patch formed on the photoreceptor is not transferred. a transfer voltage control step for
a density detection step of detecting the density of the toner patch transferred to the intermediate transfer member;
a plurality of said photoreceptors, and each of said plurality of photoreceptors corresponds to each of a plurality of colors;
each of the plurality of toner patches formed on each of the plurality of photoreceptors in the toner patch formation control step is superimposed and transferred onto the intermediate transfer member;
a position of at least one of the plurality of toner patches transferred onto the intermediate transfer member after detection by the density detection step, based on the density detected by the density detection step; A control method for an image forming apparatus, further comprising a position correction step of correcting a position of at least one toner patch among the plurality of toner patches formed between toner images of a print image. An image forming apparatus comprising a photoreceptor, a transfer section, removing means for removing toner on the surface of the photoreceptor, and an intermediate transfer body onto which the toner image formed on the photoreceptor by the transfer section is transferred. a control program for
The control program is
a print control step of performing control to form a toner image based on a print image on paper under a first formation condition using at least the photoreceptor and the transfer unit;
a toner patch formation control step of forming a toner patch on the surface of the photoreceptor under a second formation condition determined based on the first formation condition when forming a toner image on a sheet in the print control step; ,
When the toner patch formed on the surface of the photoreceptor passes through a portion facing the transfer unit, the voltage applied to the transfer unit is controlled to a voltage at which the toner patch formed on the photoreceptor is not transferred. a transfer voltage control step for
a density detection step of detecting the density of the toner patch transferred onto the intermediate transfer member;
causing a computer to execute a condition correction step of correcting the second forming condition after detection by the density detection step based on the density detected by the density detection step;
If the amount of toner patches indicated by the density detected in the density detection step is higher than a first threshold value, in the condition correction step, toner patches formed on the surface of the photoreceptor after detection by the density detection step. reduce the amount of
If the toner patch amount indicated by the density detected in the density detection step is lower than a second threshold value lower than the first threshold value, then in the condition correction step, after detection by the density detection step, increasing the amount of toner patches transferred to the surface of the photoreceptor to
A control program for an image forming apparatus, wherein the second threshold value is changed according to primary transfer efficiency, which is transfer efficiency of the transfer unit. An image forming apparatus comprising a photoreceptor, a transfer section, removing means for removing toner on the surface of the photoreceptor, and an intermediate transfer body onto which the toner image formed on the photoreceptor by the transfer section is transferred. a control program for
The control program is
a print control step of performing control to form a toner image based on a print image on paper under a first formation condition using at least the photoreceptor and the transfer unit;
a toner patch formation control step of forming a toner patch on the surface of the photoreceptor under a second formation condition determined based on the first formation condition when forming a toner image on a sheet in the print control step; ,
When the toner patch formed on the surface of the photoreceptor passes through a portion facing the transfer unit, the voltage applied to the transfer unit is controlled to a voltage at which the toner patch formed on the photoreceptor is not transferred. a transfer voltage control step for
causing a computer to execute a density detection step of detecting the density of the toner patch transferred to the intermediate transfer member;
a plurality of said photoreceptors, and each of said plurality of photoreceptors corresponds to each of a plurality of colors;
each of the plurality of toner patches formed on each of the plurality of photoreceptors in the toner patch formation control step is superimposed and transferred onto the intermediate transfer member;
further comprising a color number correction step of correcting the number of colors of the plurality of toner patches to be superimposed and transferred onto the intermediate transfer member after detection by the density detection step, based on the density detected by the density detection step; A control program for an image forming apparatus that is executed by a computer. An image forming apparatus comprising a photoreceptor, a transfer section, removing means for removing toner on the surface of the photoreceptor, and an intermediate transfer body onto which the toner image formed on the photoreceptor by the transfer section is transferred. a control program for
The control program is
a print control step of performing control to form a toner image based on a print image on paper under a first formation condition using at least the photoreceptor and the transfer unit;
a toner patch formation control step of forming a toner patch on the surface of the photoreceptor under a second formation condition determined based on the first formation condition when forming a toner image on a sheet in the print control step; ,
When the toner patch formed on the surface of the photoreceptor passes through a portion facing the transfer unit, the voltage applied to the transfer unit is controlled to a voltage at which the toner patch formed on the photoreceptor is not transferred. a transfer voltage control step for
causing a computer to execute a density detection step of detecting the density of the toner patch transferred to the intermediate transfer member;
a plurality of said photoreceptors, and each of said plurality of photoreceptors corresponds to each of a plurality of colors;
each of the plurality of toner patches formed on each of the plurality of photoreceptors in the toner patch formation control step is superimposed and transferred onto the intermediate transfer member;
a position of at least one of the plurality of toner patches transferred onto the intermediate transfer member after detection by the density detection step, based on the density detected by the density detection step; A control program for an image forming apparatus, further causing a computer to execute a position correction step of correcting the position of at least one toner patch among the plurality of toner patches formed between toner images of a print image.

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